The natural resources weekly report

WILDLIFE

Mystery in caves means huge costs for farmers

White-nose syndrome has wiped out millions of bats across the Northeast and is poised to make its way across the country. Photo courtesy of Marvin Moriarty/U.S. Fish and Wildlife Service.

For years, as dusk settled over James Roby's organic farm in Connecticut, bats feasted on the insects hovering near his crops. Counting the dark shapes swooping against the evening sky from his picnic table, Roby said he would lose track of their quick movements as the number passed a dozen.

But last year, the counting was too easy -- he normally saw no more than two bats on a given night.

A single little brown bat, one of the most common species in the United States, can eat up to 4,500 insects per night during their active season. That adds up to about 1 million insects per year for just one bat. Multiply that by the millions of insect-chowing bats in the United States, and it adds up to a whopping $22.9 billion in free pest control for farmers like Roby.

But that agricultural and economic benefit is at risk from a disease creeping from cave to cave and darkening entire colonies at a go.